Senior meteorologist Darren Ray, from the Bureau of Meteorology, said temperatures were warmer than the past two summers.

"The conditions we are seeing at the moment are actually a little bit of a contrast to some of the cooler summers we have had in 2010-2011 and last summer into 2011-2012 where we had a la nina influence... this impacts our rainfall and also our temperatures, so we had quite wet and mild summers," Mr Ray said.

"Temperatures during those summers were about a degree below average, and probably this year we're looking about a degree above average."

The last time the mercury rose above conditions experienced on Friday was in the summer of 2009, when the Riverland recorded its hottest day on record.

"During that heatwave the temperature at Renmark got up to 48.2, now that's the hottest day they have ever had on record there and that came in the middle of seven days in a row above 40 degrees," Mr Ray said.

"That's the last time we've had a hotter day than the 46 degrees experienced on Friday."

Red Cross spokesperson John Richardson advised people to take precautions.

"The best time to start to prepare for extreme heat is when it's cool," he told ABC News.

"What we do say to people, particularly those more susceptible to heat, is to look at what you might do to prepare your house, how you might look at shading, cooling, things like insulation."

The CFS has advised that smoke visible across the Riverland has drifted from fires in south-western Victoria.